Control mechanism for automatically restricting the flow of fluid in a conduit leading to hydraulically actuated means



United States Patent Inventor John S. Pilch,

Ware, Massachusetts Appl. No. 790,082 Filed Jan. 9, 1969 Patented Sept.29, 1970 Assignee Ware Machine Works, Inc.

Ware, Massachusetts a corporation of Massachusetts CONTROL MECHANISM FORAUTOMATICALLY RESTRICTING TI-IE FLOW OF FLUID IN A CONDUIT LEADING TOI-IYDRAULICALLY ACTUATED MEANS 6 Claims, 7 Drawing Figs.

11.8. CI. 91/411, 9l/410,.9l/448, 214/138, 212/66 Int. Cl ..Fl5b 11/04,FlSb 11/16 Field of Search 91 /392,

44s, 448(lT),41l,41 445 References Cited UNITED STATES PATENTS 1,877,1029/1932 Whitesell 60/52UX 2,378,497 6/1945 Phillips 91/41 1X 3,475,00010/1969 Fry et a1 91/410X FOREIGN PATENTS 551,205 5/1932 Germany 91/410Primary Examiner-Edgar W. Geoghegan Attorney-Dike, Thompson andBronstein ABSTRACT: A mechanism for automatically restricting the flowof fluid in a conduit leading between a source of fluid under pressureand hydraulically actuated means for causing pivotal movement of amember. The speed of pivotal movement of the member is rapid during oneportion of its pivotal movement but the speed is automatically reducedat a predetermined portion of its pivotal movement and such reducedspeed is maintained during at least a portion of its subsequent pivotalmovement.

2 g as a GIG N 8 n Patented Sept. 29, 197.0 1

Sheet FIG. 7

ATTORNEYS Patented Sept. 29, 1970 Sheet 3 of 5 m (0 cu INVENTOR.

JOHN S. P\LCH 22, ATTORNEYS Sheet FIG. 4

INVENTOR. JOHN s. RILCH Patented Sept. 29, 1970 Sheet 4 M5 I NVENTOR.

Patented Sept. 29, 1970 3,530,766

Sheet 5 015 ATTORNEYS CONTROL MECHANISM FOR AUTOMATICALLY RESTRICTINGTHE FLOW OF FLUID IN A CONDUIT LEADING TO I-IYDRAULICALLY ACTUATED MEANSBACKGROUND OF THE INVENTION This invention relates to means forautomatically restricting the flow of fluid in a conduit leading betweena source of fluid under pressure and hydraulically actuated means forcausing pivotal movement of a member whereby the speed of pivotalmovement of the member is rapid during one portion of its pivotalmovement but is automatically reduced during a predetermined portion ofits pivotal movement and such reduced speed is maintained during atleast a portion of its subsequent pivotal movement thereby minimizingfailures of the hydraulic system and/or the mechanism.

Many devices have members which are pivotally moved by hydraulicallyactuated means, for example, the horizontal pivotal movement of the boomcarrying the bucket of a backhoe, trencher or other excavating device.It has long been considered desirable to provide means for automaticallyslowing down the pivotal movement of such a membernear the end of itspivotal movement in order to prevent damage or injury to the apparatuswhen at the end of its pivotal movement the movement is completelystopped by mechanical stop means or by other means which causemechanical or hydraulic failures.

In my prior US. Pat. No. 3,407,946 I have disclosed a pair ofhydraulically operated jacks and a pair of throttling valves. Eachthrottling valve is operable by a cam on the turret of a backhoe torestrict the flow of fluid only in the conduit which leads from the rodend of the hydraulic jack to the main control valve during the return orinactive stroke of the ram. Because the rod of the hydraulic jack isattached to the turret, a braking effect on the pivotal movement of theturret results, and this braking effect opposes the pivoting force whichis simultaneously being exerted on the turret by the piston of the otherhydraulic jack. However, because during this braking action if theoperator continues to hold the main control valve in position to supplyfluid under full volume to the operative end of the jack which isexerting the pivoting force and also because the momentum of the loadedbucket and swinging boom is great it has been found in practice thatthese combined forces create pressures on the fluid circuit of theinactive cylinder which develop to a magnitude of between 6,000 and9,000 pounds per square inch and failures develop in use as a result ofthese excessive pressures.

Another proposed solution is disclosed in US. Pat. No. 3,343,686 datedSeptember 26, I967, in which two one-way restricter valves are provided,one in a conduit between the main control valve and the rod end of thehydraulic jack and the other in the conduit from the closed or cylinderend of the same cylinder and the main control valve. One of theserestricter valves is always closed in restricting position and restrictsall fluid that is delivered to one jack during the complete retractingcycle of this jack. In other words, all fluid delivered to this jack forthe purpose of retracting the same is restricted and it is impossible todeliver unrestricted fluid to this jack during any portion of itsretracting cycle. The other restricter valve also is always closed inrestricting position and restricts all fluid that is being exhaustedfrom this same jack during this same retracting cycle, and it isimpossible to exhaust unrestricted fluid from this jack. The only timethese valves open is when fluid is supplied by the operator to extendthe jack. Then both these valves are opened by the fluid flowing throughthem. Furthermore, these valves are-not operated by the turret. Inaddition, in this construction, itis necessary to employ three differentcylinders to cause pivotal movement of the turret making the apparatusexpensive to manufacture.

One object of this invention is to provide means for automaticallyrestricting the flow of fluid in a conduit leading between a source offluid under pressure and the operative side of hydraulically actuatedmeans for causing pivotal movement of a member whereby the speed ofpivotal movement of the member is rapid during one portion of itspivotal movement but is automatically reduced at a predetermined portionof its pivotal movement and such reduced speed is maintained during atleast a portion of its subsequent pivotal movement minimizing failuresin the hydraulic system and/or the mechanism.

Another object is to provide such an apparatus which is economical tomanufacture.

A further object is to provide such an apparatus in which the member maybe moved pivotally first in one direction and then in the oppositedirection by the use of only two hydraulically actuated means forcausing pivotal movement of said member.

Another object of this invention is to provide a means for automaticallyrestricting the flow of fluid in a conduit leading between the source offluid under pressure and the operative side of a hydraulic jack wherebythe flow of fluid delivered to the jack will be unrestricted during aportion ofits movement, and the flow of fluid delivered to this samejack will be restricted during a subsequent portion of its movement.

Other objects and advantages of the invention will be apparent from thefollowing description taken in conjunction with the accompanyingdrawings wherein a preferred embodiment of the invention is shown.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. I is a side view of a tractor mounted backhoe embody ing theinvention;

F IG, 2 is a plan view of the apparatus shown in FIG. 1;

FIG. 3 is a schematic view showing a hydraulically actuated apparatusenbodying the invention with the restricter valve actuating mechanism ina position to restrict the flow of fluid to the rod side of thehydraulically actuated means which is causing the pivotal movement;

FIG. 4 is a fragmentary plan view on an enlarged scale of the restrictervalve actuating mechanism and the restricter valves shown in FIG. 3 withone restricter valve shown in longitudinal section;

FIG. 5 is a view similar to FIG. 4, but illustrating the restrictervalve actuating mechanism in neutral position and both restricter valvesin longitudinal section;

FIG. 6 is an enlarged longitudinal section of one of the restrictervalves; and

FIG. 7 is an enlarged section of the relief valve which is cluded in thesystem.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawingswherein similar reference characters designate corresponding partsthroughout, the tractor mounted backhoe shown in FIGS. 1 and 2 comprisesthe tractor 10 having vertical pivots II for the turret 12 which carriesthe boom 13 on the end of which is pivotally connected the dipper stick14 which in turn carries the bucket 15.

The tractor is provided with the ground engaging stabilizer legs 16.

The turret I2 is adapted to be moved pivotally about a vertical axis,formed by the pivots 11, by means of hydraulic jacks l7 and 18 (FIG. 3)having rods 17B and 18B attached to their rams 17A and 18A respectively.As shown in FIG. 5, the rods 17B and 18B are pivotally connected to lugs19 and 20 through links 21 and 22 respectively so that pivotal movementsof the turret I2 and the boom 13 about pivots 11 are caused when therods are alternately moved inwardly of the cylinders 17A and 18Arespectively.

The cam 23 is carried by turret l2 and is rotatable therewith about thepivots 11.

The hydraulic system includes a customary relief valve 23 (FIGS. 3 and7) connected in the lines 26A and 27A which lead to the rod sides ofhydraulic jacks l7 and I8 and which valve is connected to the restrictervalves 24 and 25 by hydraulic conduits 26B and 273 respectively.

Restricter valve 24 is connected by hydraulic conduit 28 to main controlvalve 29 and restricter valve 25 is connected by hydraulic conduit 30 tosaid main control valve.

Each of the restricter valves 24 and 25 comprises a housing 31 (FIGS.and 6) having a longitudinal bore 32 in which is positioned a plunger 33which extends into a spring chamber 34 intermediate the ends of bore 32.The plunger is provided with spring seat 35 secured thereto. Spring 36has one end engaging spring seat 35 and its opposite end engaging poppet37 slidably mounted on plunger 33.

The cam 23 (FIGS. 3, 4 and 5) carried by turret 12 is adapted to berotated with the turret throughout the full range of pivotal movement ofthe turret which is approximately 185.

The system shown in FIGS. 3 to 5 is provided with opposed restrictervalves 24 and 25 and between the adjacent ends of the plungers 33 thereis positioned the roller 41 of cam follower 42 which is pivotallymounted at 43 on bracket 44. Cam follower 42 carries the rollers 45 and4.6 which are adapted to be engaged respectively by cam surface 23A oncam 23 depending upon the direction of pivotal movement of turret 12. InFIG. 5, the turret 12 is shown at its center position at which time thecam surface 23A does not engage either of the followers 45 or 46.

When the turret l2 and cam 23 are pivotally moved in a counterclockwisedirection from the position shown in FIG. 5 to the position shown inFIGS. 3 and 4, after a predetermined amount of such movement the camsurface 23A engages roller 46 and causes the follower 42 to,move in acounterclockwise direction about its pivot 43 and to depress the plunger33 which restricts the passage of fluid from the main control valve 29through restricter valve 25 to line 278, relief valve 23 and the rod endof cylinder 17.

This is accomplished as follows. Referring to the restricter valve 25,when the follower 42 is in the intermediate position of FIG. 5 the largeports 39 of this restricter valve afford substantially unobstructed flowof fluid from valve chamber 34 through them to passage 38 and then toconduit 278. Thus, when the operator actuates the main control valve 29to direct fluid through conduit 30, it passes substantially unobstructedthrough chamber 34, ports 39, passage 38, conduit 27B, relief valve 23,conduit 27A to the rod end of cylinder 17 as shown by the arrows in FIG.3. This causes ram 17A to move from left to right looking at FIG. 3which causes rod 178 to pivotally move the turret 12 in acounterclockwise direction at a relatively high speed from its centralposition of FIG. 5 towards its six oclock position of FIGS. 3 and 4.After a predetermined amount of such movement, the cam surface 23Aengages roller 46 which causes carn follower 43 to be rotated in acounterclockwise direction about pivot 43 and roller 41 to force plunger33 inwardly of the bore 32 of restricter valve 25, to the position shownin FIGS. 3 and 4 where the poppet 37 completely obstructs the flow offluid from chamber 34 through ports 39 to passage 38. Thereafter, thefluid flows from chamber 34 through the small ports 40 to the smallerpassage 38A, conduit 27B, relief valve 23, conduit 27A and rod end ofcylinder 17 This slows down movement of the rod and the speed of pivotalmovement of the turret and boom as they approach the six oclock positionof FIGS. 3 and 4.

During this entire cycle of pivotal movement, the large ports 39 in theother restricter valve 24 are open and they afford substantiallyunobstructed flow of fluid from rod end of cylinder 18, through reliefvalve 23, conduit 26B, valve chamber 34 to passage 38 to conduit 28 andmain control valve 29, as shown by the arrows in FIG. 3. Thus there issubstantially no restriction of the flow of fluid from the rod end ofcylinder 18 to the main control valve.

When it is desired to cause pivotal movement of the turret in aclockwise direction from its position of FIGS. 3 and 4 or from itscentral position of FIG. 5, the operator actuates the main control valve29 to cause fluid to flow through the conduit 28, valve 24, conduit 26B,relief valve 23 and rod end of cylinder 18 and this causes pivotalmovement of the turret at a rapid speed, the direction of flow of fluidin the system being opposite to the direction indicated by the arrows inFIG. 3. When the turret and boom approach the twelve oclock position,cam surface 23A engages roller 45 and causes follower 42 to rotate in aclockwise direction about pivot 43, and roller 41 slides plunger 33inwardly of chamber 32 of valve 24 thus closing communication betweenlarge ports 39 and chamber 34 and the flow of fluid through the valve isthereafter restricted because it must pass through the smaller ports 40.This reduces the speed of pivotal movement of the turret and boom duringthe latter part of this clockwise movement.

By controlling the areas of the ports 40 and the restricted passages38A, the reduction of speed of pivotal movement of the turret may bevaried as desired.

In use of this invention for moving the turret and boom of a backhoeabout a vertical axis for slightly more than it has been found thatpressures on the fluid circuit do not exceed 2,500 pounds per squareinch and that consequently failures do not develop in the system or inthe mechanism as was the case in the apparatus of my prior US. Pat. No.3,407,946. Furthermore, this is accomplished with only two cylinders 17and 18 and the cost of manufacturing the apparatus is no greater thanthe cost of manufacturing the apparatus of my said prior patent.

While a cam and follower have been shown for actuating the restrictervalves, it is pointed out that this actuation could be effected bydirect contact with the turret, through a toggle means, through alinkage means, by a small hydraulic cylinder actuator, or throughelectrical means or other suitable arrangements.

While one desirable embodiment of the invention has been shown in thedrawings, it is to be understood that this disclosure is for the purposeof illustration only and that various changes in shape, proportion andarrangement of parts as well as the substitution of equivalent elementsfor those herein shown and described, may be made without departing fromthe spirit and scope of the invention as set forth in the appendedclaims.

I claim:

I. In apparatus of the character described, in combination, a membermounted for pivotal movement, a source of fluid under pressure,hydraulically actuated means operatively connected to said member forcausing pivotal movement thereof in a predetermined direction, a maincontrol valve for directing fluid from said source of fluid through aconduit to the operative portion of said hydraulically actuated means,norrnally open valve means in said conduit and means operable responsiveto the pivotal movement of said member for partially closing saidnormally open valve means when said member reaches a predeterminedportion of pivotal movement, thereby automatically to restrict the flowof fluid through said conduit to said hydraulically actuated meansduring at least a portion of the subsequent pivotal movement of saidmember.

2. Apparatus as defined by claim 1 wherein said normally open valvesmeans comprises a first, closable passageway for the flow of fluid and asecond, permanently open passageway -for the flow of said fluid, saidclosable passageway being closable by said means operable responsive topivotal movement of said member.

3. Apparatus as defined by claim 2 wherein the second, permanently openpassageway is smaller than said first, closable passageway.

4. Apparatus as defined by claim 3, wherein the means operableresponsive to pivotal movement of said member comprises a cam on saidmember and a follower for said cam operative to move said normally openvalve means to close said closable passageway.

5. Apparatus as defined by claim 4, wherein said normally open valvemeans comprises a housing having a longitudinal bore therein and a sideaperture, said housing being connected to said source of fluid underpressure through said side aperture, a spring loaded plunger slidablydisposed in said bore, the inserted end of said plunger having alongitudinal channel with axially displaced side ports, one of said sideports forming, with said channel and said side aperture, saidpermanently open passageway and other of said ports forming with saidchannel and said side aperture, said closable passageway.

6. Apparatus as defined by claim 1 also comprising a secondhydraulically actuated means operatively connected to said member forcausing pivotal movement thereof in a direction opposite to saidpredetermined direction, a second conduit affording communicationbetween said main control valve and

